Flow of contaminated groundwater and its interaction with the ground occurs both in soil and rock. Prediction of contaminant transport and transformation is very important in planning of remedial and preventive measures and requires suitable transport and transformation models. Evidence exists in many areas of this country that substantial groundwater flow occurs in fractured rock underlying the soil; this is particularly so in the Aberjona Valley where contaminated groundwater has been found in the rock fractures. Predicting the potential contaminant transport requires fracture flow models. The present status of fracture flow models is unsatisfactory in that they are often based on unrealistic geometries, in that neither extensive parametric simulation nor field studies have been conducted and that, as a consequence, the range of applicability of continuum models is not known. The proposed three-year research has two major components. 1. It will characterize the soil and rock formation in the Aberjona Valley to provide the information for developing fracture flow models. This engineering geologic characterization is also an essential basis for most other Core B research projects. Data collection has started and will continue. In addition to the Superfund exploration wells, many other borings and surface exposures will be used for this purpose. A computer program for 3-d representation and manipulation of this data will also be developed. 2. It will develop geometric fracture system models, geometric and flow models of individual fractures, and it will then combine the geometric fracture system - and individual fracture models in fracture flow models. The fracture flow model representing flow in fractured masses will be first used to conduct computer simulations to determine which parameters and parameter states are significant; it will also be used to find the application limits between discrete fracture models and equivalent porous media models. All this will be done in the context of the Aberjona aquifer and, consequently a field validation will be conducted which will be combined with the other projects of the Aberjona field study. The field tests will provide the basis of further research in which transportation and transformation models need to be developed.